An in-trail procedure (ITP) is a protocol followed by an aircraft that desires to change its current flight level to a new flight level by descending or climbing in front of or behind one or more potentially blocking aircraft flying at an intervening flight level. In accordance with ITP criteria, certain conditions must be satisfied before the flight crew member issues a request for clearance to proceed with the flight level change. Whether or not the conditions are satisfied will depend on a number of dynamically changing factors associated with the host aircraft and other aircraft, such as the current geographic position of the aircraft, the current speed of the aircraft, the current heading of the aircraft, the desired new flight level, and the current flight level.
Modern flight deck instrumentation might include a traffic display that provides a two-dimensional representation of a host aircraft and neighboring aircraft. Such display systems typically provide a number of parameters and visual indicators that enable a pilot to form a quick mental picture of the vertical situation of the host aircraft. For example, such a system might include displays of an aircraft symbol, the aircraft altitude, the vertical flight plan, and terrain. In this manner, a member of the aircraft flight crew can obtain information related to the vertical situation of the aircraft relative to other aircraft with a simple glance at the display system.
Such a system could be used to identify the vertical position of potentially blocking aircraft for purposes of an ITP. However, it is possible that at the moment when the pilot views the ITP display, (1) an intermediate flight level is blocked by traffic that does not meet the ITP distance/speed criteria or (2) the desired flight level is not available because traffic is present with which the host aircraft cannot maintain the standard separation when it climbs to the desired flight level, notwithstanding that at a later time, the opportunity for the ITP transition might exist. It may be necessary for the pilot to repeatedly scan the ITP display in order to detect an opportunity for an ITP transition because the display does not provide any information regarding when an opportunity for a transition to the desired flight level will arise. Thus, the pilot's work load is increased.
Considering the foregoing, it would be desirable to provide a system and method for providing a graphical/textual indication on an ITP display that is representative of the time when an opportunity for an ITP maneuver will be available.